The BATT Program is supported by the U.S. Department of Energy Office of Vehicle Technologies (OVT) and is managed by the Lawrence Berkeley National Laboratory (LBNL) as part of its Carbon Cycle 2.0 initiative. BATT investigators in top research universities and institutions work on six Task Areas: Anodes, Cathodes, Electrolytes, Cell Analysis, Diagnostics, and Modeling.
Yi Cui, Stanford University
A method was developed to synthesize Si porous structures for Si batteries directly from agricultural waste products rice husks. Rice husks were first converted to pure silica by burning in air and then reduced to silicon by magnesium. The synthesis process results in a 5 wt% yield of Si according to the weight of the initial rice husks. Considering the abundance (1.2×108 tons/year) and the low price (~$18/ton) of the rice husks, the synthesis dramatically reduces the cost of nanostructured silicon, which may paves the way for large scale application of Si anodes in vehicles.
Donghai Wang’s group at the Pennsylvania State University has developed novel, silicon-carbon (Si-C) composite that possesses primary carbon-coated sub-10 nm Si particles and secondary micro-sized aggregation. Because of this unique structure, the as-synthesized Si-C composite anode can deliver a high reversible specific capacity (~1600 mAh/g) with excellent cycling stability over 150 cycles.
Nitash Balsara, LBNL
Lithium-sulfur cells are attractive targets for energy storage applications as their theoretical specific energy of 2600 Wh/kg is much greater than the theoretical specific energy of current lithium-ion batteries. Unfortunately, the cycle-life of lithium-sulfur cells is limited due to migration of species generated at the sulfur cathode. These species, collectively known as polysulfides, can transform spontaneously, depending on the environment, and it has thus proven difficult to determine the nature of redox reactions that occur at the sulfur electrode.
Karim Zaghib, Hydro Quebec (Montreal, Canada)
The objective of this project is to develop high-capacity, low-cost electrodes with good cycle stability to replace graphite in Li-ion batteries. The challenge of this work is to stabilize the Si-anode capacity which requires studying the architecture of the electrode and controlling the stress.
Dean Wheeler and Brian Mazzeo of Brigham Young University (Provo, UT) have developed a new surface probe that can accurately measure electronic conductivity of intact electrodes. Measuring conductivity of intact thin-film electrodes (still attached to current collector) is difficult, and prior methods have not been sufficiently accurate and robust. The new method uses four small parallel lines to contact the surface with controlled applied pressure. The method also allows simultaneous measurement of bulk film conductivity and contact resistance between the film and the current collector.
Gao Liu at LBNL has developed a new kind of composite anode based on silicon that can absorb eight times the lithium of current Li-ion batteries and maintains a high capacity of 2100 mAh/g in Si after 650 cycles.
Yi Cui, Stanford University
Silicon is a promising next-generation anode material for high-energy lithium-ion batteries due to its high specific capacity, which is theoretically 10 times greater than graphite. However, its cycle life is limited due to volume expansion and fracture during lithium reaction. This degradation of the Si results in loss of electrical connection and pulverization of the electrode. Several fundamental studies still need to be conducted to develop viable Si electrodes for batteries. Yi Cui’s group at Stanford University is working on understanding the properties of various Si nanostructures and is designing new ones based on particles and wires that target improving Si cyclability.
Oleg Borodin at the Army Research Laboratory has developed and validated a polarizable force field for a wide class of ionic liquids (ILs), which are being explored as additives to lithium-battery electrolytes for improved stability.
The Zaghib Group at Hydro-Québec has used in situ SEM to see SiOx particles grow and shrink during cycling. SiOx is a promising anode material for Li-ion batteries due to a high theoretical specific capacity of 1338 mAh/g and less volume change than Si upon charge-discharge. Analysis of the morphology changes in SiOx particles provides insight into the failure mode associated with capacity fade on cycling.
The Persson and Kostecki Groups, in collaboration with other BATT investigators, have quantified lithium-ion diffusivity as a function of transport direction in graphite anodes. Electrochemical experiments combined with first-principles calculations indicate that lithium diffusion in graphite is several orders of magnitude faster in the direction parallel, as opposed to perpendicular, to the graphene plane. These results provide guidelines for designing graphite anodes with preferential orientation for higher rate capability, which translates to faster charging batteries.
BATT Scientist Prof. Nitash Balsara (UC Berkeley and Lawrence Berkeley National Laboratory) was selected as a new 2014 fellow of the Neutron Scattering Society of America (NSSA) for sustained, high impact, neutron scattering research on a broad range of polymeric materials, and for organizational, mentoring and leadership activities in promoting the use of neutron scattering […]
Gerbrand Ceder, MIT and Kristin Persson, LBNL made the cover of the latest Scientific American with their article: “How Supercomputers Will Yield a Golden Age of Materials Science”. Check it out!
Here’s the clip of Dr. Persson’s presentation, A Google for Materials